Straightness belongs to the form tolerances. Form and position tolerances represent a subarea of Geometric Product Specifications (GPS). They provide a way of using technical drawing entries to tolerate the geometric deviation of components. The straightness requirement specifies how perfectly straight a measured object must be. It is applied to straight lines, not planes, and represents a curve in the centerline or generatrix. Therefore, straightness is used to describe distortion tolerances of long objects. Straightness can be negatively affected by horizontal or vertical curvature, roll, screw or surface defects. Depending on which measuring method is used, these deviations become more or less visible so that they can be recorded in the desired level of detail. Which mechanical adjustment is chosen is as important as the selection of the measuring method and equipment. To measure the straightness of an object, 3D coordinate measuring machines, among others, are particularly suitable. A professional assessment is in any case the right way to find a suitable measuring method.